diff options
| author | Kristina Martsenko <kristina.martsenko@arm.com> | 2023-05-09 15:22:31 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2023-06-05 17:05:41 +0100 |
| commit | 8536ceaa747174ded7983f13906b225e0c33ac51 (patch) | |
| tree | 9b4743616447691e73ea44b77221bce88133f197 /arch/arm64/kernel/traps.c | |
| parent | 3172613fbcbb0634d91d05601f029da0c1466999 (diff) | |
arm64: mops: handle MOPS exceptions
The memory copy/set instructions added as part of FEAT_MOPS can take an
exception (e.g. page fault) part-way through their execution and resume
execution afterwards.
If however the task is re-scheduled and execution resumes on a different
CPU, then the CPU may take a new type of exception to indicate this.
This is because the architecture allows two options (Option A and Option
B) to implement the instructions and a heterogeneous system can have
different implementations between CPUs.
In this case the OS has to reset the registers and restart execution
from the prologue instruction. The algorithm for doing this is provided
as part of the Arm ARM.
Add an exception handler for the new exception and wire it up for
userspace tasks.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20230509142235.3284028-8-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/traps.c')
| -rw-r--r-- | arch/arm64/kernel/traps.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 4bb1b8f47298..32dc692bffd3 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -514,6 +514,57 @@ void do_el1_fpac(struct pt_regs *regs, unsigned long esr) die("Oops - FPAC", regs, esr); } +void do_el0_mops(struct pt_regs *regs, unsigned long esr) +{ + bool wrong_option = esr & ESR_ELx_MOPS_ISS_WRONG_OPTION; + bool option_a = esr & ESR_ELx_MOPS_ISS_OPTION_A; + int dstreg = ESR_ELx_MOPS_ISS_DESTREG(esr); + int srcreg = ESR_ELx_MOPS_ISS_SRCREG(esr); + int sizereg = ESR_ELx_MOPS_ISS_SIZEREG(esr); + unsigned long dst, src, size; + + dst = pt_regs_read_reg(regs, dstreg); + src = pt_regs_read_reg(regs, srcreg); + size = pt_regs_read_reg(regs, sizereg); + + /* + * Put the registers back in the original format suitable for a + * prologue instruction, using the generic return routine from the + * Arm ARM (DDI 0487I.a) rules CNTMJ and MWFQH. + */ + if (esr & ESR_ELx_MOPS_ISS_MEM_INST) { + /* SET* instruction */ + if (option_a ^ wrong_option) { + /* Format is from Option A; forward set */ + pt_regs_write_reg(regs, dstreg, dst + size); + pt_regs_write_reg(regs, sizereg, -size); + } + } else { + /* CPY* instruction */ + if (!(option_a ^ wrong_option)) { + /* Format is from Option B */ + if (regs->pstate & PSR_N_BIT) { + /* Backward copy */ + pt_regs_write_reg(regs, dstreg, dst - size); + pt_regs_write_reg(regs, srcreg, src - size); + } + } else { + /* Format is from Option A */ + if (size & BIT(63)) { + /* Forward copy */ + pt_regs_write_reg(regs, dstreg, dst + size); + pt_regs_write_reg(regs, srcreg, src + size); + pt_regs_write_reg(regs, sizereg, -size); + } + } + } + + if (esr & ESR_ELx_MOPS_ISS_FROM_EPILOGUE) + regs->pc -= 8; + else + regs->pc -= 4; +} + #define __user_cache_maint(insn, address, res) \ if (address >= TASK_SIZE_MAX) { \ res = -EFAULT; \ @@ -824,6 +875,7 @@ static const char *esr_class_str[] = { [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", + [ESR_ELx_EC_MOPS] = "MOPS", [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", [ESR_ELx_EC_SERROR] = "SError", |